Dynamo-electric machine or motor.



No. 694,293. Patented Feh.`25, |902.

W. FLV. MARSHALL. DYNAM ELECTRIC MACHINE 0R MTR. (Application med Nov. s, 1901.) (Np Model.) 2 Sheets-,Sheet I.

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y No. 694,293.` Patented Feb. 25, |902.

W. R. V. MARSHALL. l f

DYNAMO ELIECTRIC MACHINE 0R MOTOR.

(Application med Nov. s, 1901.)

(No Model.) 2 Sheets-Sheet 2.

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DYNAVIO-ELECTRIC MACHINE R MOTOR.

SPECIFICATION forming part 0f Letters Patent N 0. 694,293, dated. February 25, 1902.

Application tiled November 8, 1901. Serial. No. 81,574. (No model.)

and motors, so that thereaetion of the arma ture shall be checked to alarge extent, thus enabling a number of practical advantages to be obtainedsuch,for example,among others, as comparatively nearly sparkless commutationand increasing the capability of the dynamo or motor to take overloads with very small risk of damage.

My improved poleface may be constructed in various ways; but in all the modifications it consists, essentially, of laminated plates of iron or steel with intervening non-magnetic spaces between each plate or set of two or more plates, transverse non-magnetic spaces being also formed in some cases, if desired. The

plates may be secured in any suitable manner; but they are by preference arranged in groups and strung on binding-rods, so that each series of groups overlap or break joint and so that the greatest breadth is at the center of the pole-face.

Figure l of the accompanying drawings is au elevation, partly 4in section, of one modification of my improved pole-face, showing a part of the pole to which it is attached. Fig. 2 is an inverted horizontal section of the said pole-face. Fig. 3 is a diagrammatic face View of the pole-face with the iron irregularly distributed. Y

In carrying out my invention according to the modification shown in Figs. l and 2 each -pole-face consists of a number of standard segmental iron or steel plates A, curved to suit the armature (not shown) and having holes -formed through them, so that they may be strung on binding-rods B, extending between side plates or cheeks C. The plates A are by preference arranged in sets of two or more plates each, (three being shown in this example,),distance-pieces D being placed between adjacent sets of plates and between them and the side binding-plates C, where necessary, so that the plates A are held in such a Way that spaces E are left between adjacent sets of plates. Instead of the plates A being in sets single plates may be used, as indicated in Fig. 3.

The relative amounts of metal and nonmagnetic spaces in the pole-face are dependent upon the class ot work the dynamo or motor has to do, whether there is to be a constant load or not, power of taking overload,

whether or not to run equally well in either direction of rotation, also upon theinaterial used in the pole-face and iield, also quality of ironin armature; but a description of the action of the pole-face will explain the best construction to select.

In Fig. l,` assuming the armature of a dynamo as revolving clockwise, the reaction or distorting effect of the armature will tend to reduce the density at K and increase it at G. Now the length of the iron ot' the pole-face at G and the density (magnetic density, therefore indirectly the sectional area of the iron at G) must beso selected that when the armature reaction comes into effect attempting to strengthen the field the magnetic reluctance shall be such that it prevents too high a density (magnetic) occurring, and if the iron is worked at a fairly high density it is well known that a considerable increase in the magnetizing power only increases the amount of magnetism very slightly. Therefore with my construction of pole-face a rising power of magnetism, such as occurs at point G in this case, does not give aproportional rise in magnetism, such as would. .occur were the ordinary air reluctance depended upon. In a like manner at point K, Where the field is being reduced, the reduction of magnetism is not so great, as the iron acts as a sort of spring, andas the density falls away, or, more correctly, as the magnetizing power gets opposed by the armatures reaction, the magnetism does not vtall away in proportion as it would do with an ordinary air reluctance; but the iron ot' my poleeface now (that is to say, at a reduced density) only requires very little power to drive the lines across it, and there by you keep what may be called a reserve power that comes into action on the air-gap and keeps up the density. It will also be observed from the foregoing that it is not essential to have a regular section of air and iron throughout the pole-face; but beneficial results could be obtained b y selecting the sections throughoutl the length to suit any special construction of a machine for special duties, such as a dynamo or motor running in one direction and having a constant load. You could then arrange your plates so that at this special load you would attempt to keep the magnetic field as near a constant density as possible, as you would then get maximum output with minimum hysteresis losses, as the hysteresis losses are dependent upon the highest density,and instead of having only the trailingpole-tip,\or, more correctly, the airgap under the trailing tip, at a high density you could arrange to keep the density high throughout the Whole length, thus increasing the output of the machine.

It will be seen that the relation of section and length of iron in pole-face at certain points instead of being of regular construetion, as shown, may be regular, dependent upon specific results required and also dependent upon class of materials used. Thus in the diagram, Fig. 3, I have indicated the plates as grouped or assembled in greater or closer mass in certain parts of the pole-face than in others, and at x I have indicated the plates of one group overlapping the plates of another group, still leaving the airgaps, hereinafter referred to, substantially at right angles to the path of the armatures magnetic reaction. This method of governing the iields distortion gives comparatively sparkless commutation under all conditions of working and enables a reduction in the number of commutator-sections lo be effected. Hysteresis losses in the armature are also reduced, enabling the size of the armature to be reduced. A saving in copper is also effected through reduction in the number of ampere turns on the field-magnets necessary to obtain the necessary field for sparkless commutation with consequent reduction in the size of the field-magnets and yoke. To assist in obtaining these results, additional air or nonmagnetic gaps or spaces L may also, if desired, be introduced into the path of the mag netie lines of force produced from the armature by arranging the plates A and non-magnetic spaces Ein a series of groups M and leaving the spaces L between the ends of the groups NI. The groups M may be attached to the pole l? by screws (shown by dotted circles Q in Fig. 2) and are so strung on the binding-rods B or otherwise secured together that the several series of groups M overlap or break joint, the greatest breadth being at the center of the pole-face, Fig. 2, and this enables the armature-conductors to gradually come into the magnetic field and to leave it in the same way, (as happens when a round pole-face is used,) thus doing away with the necessity of opening out the main air-gap .I at the point where the armature-conductors enter and leave the magnetic field in order to prevent damage to the teeth of the armature and vibration and also giving an iron reluctance for the armatures reaction or distorting effect to work upon, which under my method of construction assists in obtaining the desired result of checking the distorting effect of the armatures reaction. Instead of building up the pole-face so that its greatest breadth is at the center my improved construction of laminated plates Aand intervening non-magnetic spaces E may be grouped or held together s o that the face will be of the usual rectangular form, and Where the transverse non-magnetic spaces L are not used the plates may be in one continuous length, if desired.

I claim as my invention- I. A pole-face for a dynamo-electric machine or motor, comprisinglaminated groups of metal plates, spaces between the ends of such groups, the outside groups forming a face of less breadth than the center ones and the intermediate groups being in step-like position between the center and outside groups, substantially as described.

2. Apole-face for dynamo-electric machine or motor, comprising laminated groups of metal plates, spaces between the plates of the groups, spaces between the ends of the groups, and said groups being arranged step-like from the outside toward the center, substantially as set forth.

3. A pole-face for a dynamo-electric machine or motor, having standard plates mounted in groups, the plates of each group being spaced apart from each other, substantially as described.

4. A pole-face for a dynamo-electric inachine or motor, having standard plates mounted in groups, the plates of each group being spaced apart and being made short to leave transverse air-gaps in said pole-face, substantially as described.

5. A pole-face for a dynamoelectric machine or motor, comprising plates mounted in groups, the plates of each group being spaced apart, transverse slots in said poleface, said metal plates forming a face of greatest breadth at the center of the poleface, and diminishing in breadth in step-like manner toward the side, all substantially as described.

6. A pole-piece for a dynamo-electric machine or motor having a greater proportion of metal in one part than in another, and consisting of a number of standard metal plates assembled in such a manner as to produce a pole-face having different masses of iron in such places as it may be required according to the use of the machine, substantially as described.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

VVILFRED R. V. MARSHALL.

Witnesses:

DAVID FERGUSON, GEORGE PATTERSON.

IIO 

